@article{JRAM_1931__165_149770,
     author = {Ludwig Bieberbach},
     title = {Bemerkungen zum dreizehnten {Hilbertschen} {Problem.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {89--92},
     year = {1931},
     volume = {165},
     zbl = {0002.18701},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1931__165_149770/}
}